HVRC refuses to fix my in warranty Samsung device

I handed my in warranty Samsung S3 mini at the mtn store in Rustenburg. The phone is still on a contract from MTN. I submitted it with a box and proof pf purchase. The person there even took my original proof and gave me copies of what i jave submitted. I still have them. The guy at the store somehow failed to submit my proof of purchase to the repair centre. The HVRV repair centre sent me an sms with a quote of over R1200. I queried and was told they didn't receive the proof of purchase. I went to the Rustenburg branch, the guy there told me that he did send it and doesn't know why they didnt receive it but he will resend it anyways. I contacted HVRC and told them that. They than sent an sms saying that i must still pay a service fee of R330 because they didnt receive a proof of purchase but they will fix it. I told them i wont pay a cent because of mistakes within their company. They later sent an sms saying theres nothing wrong with the device. I must pay a service fee and collect it. <br> <br> Please repair my in warranty and MTN contract device.